By scanning people's brains while showing them movie clips, scientists better understand how different brain regions work together to recognize faces, process conversations and perform more complex cognitive functions.
Researchers from the Massachusetts Institute of Technology used functional MRI scans to track which brain regions activated when 176 young adults watched scenes from "The Social Network," "Home Alone" and "Inception." Functional MRI is a type of MRI that tracks blood flow in the brain, helping doctors plan brain surgeries by "mapping" brain activity.
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The MIT study used functional MRIs to create the most detailed functional map of the brain to date. Previous research had only used functional MRIs on people who weren't actively engaged in a task or exposed to external stimulation. But using it on people as they watched movie clips provided new insights.
"With resting-state fMRI, there is no stimulus — people are just thinking internally, so you don't know what has activated these networks," Reza Rajimehr, an MIT neuroscientist who led the study, said in a release. "But with our movie stimulus, we can go back and figure out how different brain networks are responding to different aspects of the movie."
In the study, published Wednesday in the journal Neuron, artificial intelligence helped the researchers identify the parts of the brain – specifically in the cerebral cortex – that activated scene-by-scene, relating to whatever was happening on the screen. The researchers ultimately identified 24 brain networks that activate when people recognize human faces or bodies, interpret social interactions and engage in other types of cognitive processing.
When the movie content was more nuanced or harder to follow, parts of the brain involved with executive control became dominant. During less complicated scenes, brain regions responsible for specific functions were more active. For instance, in scenes that showed actors having a straight-forward conversation, the brain region involved in language processing prevailed.
Researchers averaged brain activity across the group of people involved in this study. Further research could be more individualized, Rajimehr said.
"In future studies, we can look at the maps of individual subjects, which would allow us to relate the individualized map of each subject to the behavioral profile of that subject," Rajimehr said. "Now, we're studying in more depth how specific content in each movie frame drives these networks – for example, the semantic and social context, or the relationship between people and the background scene."